Drought, like global warming, is a slow motion event that humans can't get seem to get ahead of. Or properly grasp. For a good historical case study examining how the Maya, the Vikings, and the U.S. (in the lead-up to the Dust Bowl) each responded to drought, see this paper by Ben Orlove, who observes:
From the comparative history of the past, it can be seen how fragile human societies can be and how resistant they can be to changing established patterns of action; it can also be seen that most people somehow survive in both a biological and a cultural sense.
The big difference today, obviously, is that we know this history and also have some ability to see into the future, as this new study suggests:
The United States and many other heavily populated countries face a growing threat of severe and prolonged drought in coming decades.
What's notable about this research by Aiguo Dai, a scientist at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado, is that there's a global warming angle:
The detailed analysis concludes that warming temperatures associated with climate change will likely create increasingly dry conditions across much of the globe in the next 30 years, possibly reaching a scale in some regions by the end of the century that has rarely, if ever, been observed in modern times.
Before going any further, it's important to point out that modern times (especially in the U.S.) are not the best measuring stick, which this definitive paper succinctly explains in its abstract:
Severe drought is the greatest recurring natural disaster to strike North America. A remarkable network of centuries-long annual tree-ring chronologies has now allowed for the reconstruction of past drought over North America covering the past 1000 or more years in most regions. These reconstructions reveal the occurrence of past "megadroughts" of unprecedented severity and duration, ones that have never been experienced by modern societies in North America.
This in no way diminishes the threat of natural occurring droughts worsened by anthropogenic global warming, which NCAR's Dai lays out in his new study. Those findings are bound to make a splash in the media and blogosphere today. To understand why, here's Dai in an early MSNBC report:
We are facing the possibility of widespread drought in the coming decades, but this has yet to be fully recognized by both the public and the climate change research community. If the projections in this study come even close to being realized, the consequences for society worldwide will be enormous.
So it's a safe bet that the hook to this story is going to be climate change. Fair enough. Dai makes that explicit in his paper (which people should read). But he also concludes on this note:
Given the dire predictions for drought, adaptation measures for future climate changes should consider the possibility of increased aridity and widespread drought in coming decades.
I don't expect that message to be emphasized in the spot reporting of the study or much discussed by climate bloggers, but given the history of prolonged droughts and civilization, here's hoping it echoes in the halls of policymakers and planners.
